Quality install testing procedures for forced air systems
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This document discusses procedures for testing forced air HVAC systems to ensure quality installation and optimal performance. Key tests described are measuring total external static pressure (TESP) and air flow in cubic feet per minute (CFM). High or unbalanced static pressure can reduce efficiency and comfort, while insufficient air flow impacts humidity control, indoor air quality, and system function. The document provides examples of how to measure TESP and CFM using tools like manometers, static probes, and hot wire anemometers. Identifying issues like restrictive filters or ductwork through testing can lead to solutions that improve a system's efficiency and owner's experience.
Quality install testing procedures for forced air systems
- 1. Quality Install Testing Procedures for Forced Air Systems
- 2. Quality Installation: Outcomes • Installation practices have links to • Comfort • Humidity Levels (dehumidification) • Reduced Utility Consumption • Indoor Air Quality
- 3. Why Test? • SEER reduced when airflow not correct • High Static = more power draw on ECMs • ECMs start to draw more power at .8” wc • Must know system performance to consider ECM upgrade
- 4. Why Test? • Coils, filters, ductwork (flexible lines worst), registers all add to Total External Static Pressure (TESP) • High static pressure makes more noise • Flow directly effects comfort • No test is just a guess
- 5. Two Main Tests • Total External Static Pressure • Air Flow CFM
- 6. What is Rated TESP?
- 7. What is TESP? All components add resistance. Too much restricts flow.
- 8. Testing TESP Static Pressure Tube and Manometer
- 9. Testing TESP Pitot Tube and Manometer
- 10. Testing TESP (Heat Only) • TESP = top of heat exchanger to bottom of blower (after filter) • Pressure Drop = change over a distance (AC coil, filter, etc. • Check rating (includes coil? Filter?)
- 11. Testing TESP Rooftop units • TESP = Supply and return • Pressure Drop = change over a distance (AC coil, filter, etc. • Rated TESP, coil included in package units.
- 12. Testing TESP • TESP = Add two numbers together • Pressure Drop = subtract numbers (ignore ± sign)
- 13. TESP Results • Think Golf and Blood Pressure • Lower is better • High numbers indicate a problem • And a need for…more practice, exercise and tweaking the system
- 14. Example w/no and dirty filter • 10 After coil • 6 After coil • 4 Before Filter • 4 Before Filter • 10 After Filter • 52 After Filter • 70 Before Coil • 43 Before Coil • **TESP = 80 • ***TESP total = 95 • **∆P Coil = 62 • ∆P Coil = 38 • ∆P Filter = 2 • **∆P Filter = 48
- 15. Testing Air Flow (CFM) • Static Pressure affects air flow • Air flow determines efficiency • Need air flow to set refrigerant • Need 400~ cfm per ton of cooling • Need to know # of tons
- 16. Testing Air Flow True Flow Meter®
- 17. True Flow Meter® • Energy Conservatory, MN Manufacturer • Advantages: very accurate, fairly easy to set up • Disadvantages: Equipment can be expensive, needs filter slot that fits plates, can be effected by poor duct design
- 18. True Flow Meter® • Install in filter slot • Meter automatically averages flow rates • Needs manometer (pressure gauge)
- 19. Testing Air Flow Hot Wire or Mini-Vane Anenometer
- 20. Hot Wire or Mini Vane • Advantages: Fast and east to use, accurate (when compared to True Flow meter) • Disadvantages: Cost, need linear section of duct
- 21. Hot Wire or Mini Vane • Drill holes in duct • Take readings • Meter automatically calculates flow rates
- 22. Testing Air Flow Hotwire or Mini-Vane Anenometer
- 23. TESP • Advantages: Low cost, Quick and easy (if table available), good for troubleshooting • Disadvantages: Fan tables sometimes not available (can use generic), duct configurations may cause turbulence
- 24. TESP • Take readings • Know fan speed setting, rated TESP • Match readings off fan table to find CFM
- 25. Fan Table
- 26. Potential Problems Found Restrictive filter (up to 50% drop in flow) Restrictive designer registers
- 27. Potential Problems Found Dirty AC Coils Owner did not know it existed
- 28. Potential Problems Found Dirty Fan Blades Leaky Ductwork
- 29. Possible Solutions • Less restrictive filters • Regular filter changes, maintenance • Curved ductwork, turning vanes • Registers with free air • Smooth ductwork, not flex duct • Proper sizing of ductwork • Sealing ductwork
- 30. Challenges • Additional testing often means more cost • Additions to ductwork can add cost to proposal • “Low Bid” vs. most responsible bid • Customer education • Contractor education
- 31. Benefits • Energy Savings (that is expected and predicted) • Increased Comfort • Better customer service
- 32. Thank You Bruce Stahlberg, CEM Affordable Energy Solutions, Inc. Minneapolis, MN